Computing devices are routinely used at work, at home, and everywhere else. Computing devices advantageously enable electronic communication, data sharing (e.g., documents, pictures, music, film, etc.), the use of application-specific software, and access to information for electronic commerce through the Internet and other computer networks.
The term computing device generally refers to desktop computers, laptop computers, mobile computing devices (e.g., personal digital assistants (PDAs), cell-phones, etc.), as well as any other type of computer system. A computing device typically includes a processor and a memory as well as other types of electronic devices, such as, a disk drive.
Disk drives typically employ a moveable head actuator to frequently access large amounts of data stored on a disk. One example of a disk drive is a hard disk drive. A conventional hard disk drive has a head disk assembly (“HDA”) including at least one magnetic disk (“disk”), a spindle motor for rapidly rotating the disk, and a head stack assembly (“HSA”) that includes a head gimbal assembly (“HGA”) with a moveable transducer head for reading and writing data. The HSA forms part of a servo control system that positions the moveable head over a particular track on the disk to read or write information from and to that track, respectively.
During disk drive manufacturing, a disk drive typically undergoes a variety of tests and procedures to configure and validate the proper operation of the disk drive. Because disk drive testing represents such large expenditures for disk drive manufacturers, more efficient test equipment and testing procedures are continuously sought after in order to reduce inefficiencies and costs and to increase disk drive throughput.
In particular, when assembling the mechanical components to form the disk drive, servo patterns are written on the new disks to prepare the disk drive for customer use. However, there are often cases when the servo patterns need to be re-written. In those cases, existing servo patterns have to be erased and new servo patterns have to be re-written. For example, servo patterns have to be re-written when the initial servo writing fails, or if the servo writing was successful—but the disk drive fails functionality tests, along with many other disk drive testing situations.
As one particular example of servo writing, many disk drives have the capability to self-servo write servo sectors. During self-servo writing, the internal electronics of the disk drive are used to write the servo sectors. One technique used in self-servo writing disk drives is for the head of the disk drive to write a plurality of spiral reference patterns to the disk which are then processed by the disk drive to write the servo sectors along a circular path. For example, the spiral reference patterns may be written by moving the head from an outer diameter of the disk to an inner diameter of the disk. In the self-servo writing process, the head then writes the final servo sectors by servo-ing on the seeded spiral patterns.
However, during the spiral reference pattern writing process, errors may occur that affect the radial and circumferential position and slope of the spiral reference patterns and degrade the spiral patterns. If there are any failures during the spiral writing process, the disk may need to be fully erased before re-writing can occur. Unfortunately, this requires an additional amount of time and cost to fully erase and then re-seed the disk.
Bulk erase tools have been previously used as a magnetic device to erase the servo patterns on the disk of a disk drive. The advantage of using the bulk erase tool over using the head to erase within the hard disk drive is the fast and easy operation of the bulk erase tool. However, current bulk erase tools used in disk drive testing do not adequately erase servo patterns in an efficient enough manner. Accordingly, more efficient bulk erase tools are sought after.